1. Field of the Invention
This invention relates to positive pressure filter units adapted to be continuously operated and more particularly relates to rotary drum filters capable of filtering solids from all types of liquids including volatile and high temperature material. The filter units are encased in pressure vessels to force filtrate through the drum periphery under relatively high positive pressures to collect solids from the drum periphery and to sequentially compact and eject the solids without stopping the filtration or losing pressure.
2. Description of the Prior Art
Heretofore known rotary drum filter units could only be operated with gravity or suction drainage of the filtrate thus limiting the pressure differential through the drum periphery to a small degree. Even the most efficient suction pumps could not maintain a pressure differential above about 12 PSI. Further, such units could not filter volatile or high temperature materials. On the other hand, known positive pressure actuated filter units could only be batch operated because the pressure vessel had to be frequently opened to remove the filter cake.
It would therefore be an improvement in this art to provide rotary drum pressure filtration, preferably pre-coat rotary drum pressure filtration, and it would particularly be an improvement in this art to compact the filtered solids from the rotary drum and sequentially discharge these solids in the form of plugs without slowing up the continuous positive pressure rotary drum filtration or losing pressure.